The present invention relates to crucibles for fusion of a specimen for analysis and particularly to a porous ceramic crucible.
Analyzers for the determination of elements such as carbon, nitrogen, hydrogen, oxygen, sulfur or other substances, such as protein, rely upon the combustion of a weighted quantity of a sample in a gas flow-through system for determining the byproducts of combustion. The gases are passed through absorption and purification stages and supplied to an analyzer to measure the resultant elements of interest. One such analyzer is disclosed in U.S. Pat. No. 4,573,910 assigned to the present assignee. Typically, such analyzers integrally include a furnace which may be a resistance furnace, induction furnace or other type furnace which heats a specimen within a crucible to combustion temperatures in the range of 1000.degree. C. To assist in complete combustion, typically a lance tube is employed and directs a carrier gas into the open mouth of the crucible during heating to facilitate combustion of the sample. The gaseous byproducts of combustion subsequently flow around the outer periphery of the lance tube and/or crucible into the analyzer from the furnace.
The difficulty with such system is that the crucibles frequently can only be used for approximately 40 to 80 analyses. Accordingly, there exists a need for a crucible which not only can be used repeatedly but which also promotes the release of specimen gases during combustion.